Enhancing the crystallinity and heat resistance of poly(ethylene terephthalate) using ZnCl2-ionized polyamide-66 as a heterogeneous nucleator

To achieve the maximal improvement in the crystallization rate and heat resistance of poly(ethylene terephthalate) (PET), 2.6 mol% of ZnCl2 ionized polyamide (PA)-66 (PA-66-Zn), with a strong coordination ability, is prepared and used as PET nucleator. This study found that the PA-66-Zn heterogeneously nucleates PET more effectively than the CaCl2-ionized PA-66 and non-ionized PA-66 by differential scanning calorimetry, crystallization kinetics, X-ray diffraction, and polarized optical microscopy. This is probably a result of the introduction of stronger ion-dipole interactions (IDIs) between the PET esters and the ionized-PA-66 ZnCl2-coordinating amides, which obviously heightens the PET/PA-66-Zn interfacial compatibility. As shown by scanning electron microscopy, the compatibilization through an appropriate concentration of IDIs promotes the formation of smaller and denser PA-66 crystals with immensely increased nucleator efficiency. Furthermore, the PET/PA-66-Zn with significantly improved crystallinity displays a remarkable increase in heat-resistant temperature, at 21.6 and 55.1 degrees C higher than that of PET/PA-66 and PET, respectively. The results demonstrate that the PA-66-Zn can act as a superior nucleator and as an outstanding heat-resistant agent for PET.

Automated summary

In this study, it was found that the ionized polyamide-66 (PA-66) with 2.6 mol% of ZnCl2 (PA-66-Zn) could effectively nucleate poly(ethylene terephthalate) (PET) more than CaCl2-ionized PA-66 and non-ionized PA-66. This is attributed to the stronger ion-dipole interactions (IDIs) between PET esters and the ionized-PA-66 ZnCl2-coordinating amides, which enhances the interfacial compatibility between PET and PA-66-Zn. The PET/PA-66-Zn also exhibited significantly improved crystallinity and heat resistance compared to PET/PA-66 and PET.